up his ass
up her ass
meaning someone who is always on another persons case, like always together but even closer together, like 2 buddies hanging out, but one sayz y r u up my ass so much, or y r u up her ass so much...see get off my dickinvadeing one's space to much
being stuck together like glue, u might think of anal sex, but not this time...

i like being up everyones ass, but i hate when everyone is up my ass....
poparatzis r always up my ass...
my mother is always up my ass about homework...
girl: my bf is up my ass so much i bleed everytime he's up there!!!